Disable OS specific defines

[mrjbom]

I'm using a cross-compiler for my project and I'm having problems with how IntelliSense interprets the __linux__ define

For this code

#ifdef __linux__
#error "This is not intended to be compiled for Linux"
#endif

IntelliSense show that __linux__ is defined to 1 and i get error in VS Code
However, when I use my cross-compiler, I do not get errors, because __linux__ is not declared there
I would like to make it so that IntelliSense also doesn't see __linux__ define

Here are my IntelliSense settings

{
        "name": "i686",
        "includePath": [
            "${default}",
            "/home/username/opt/cross/lib/gcc/i686-elf/11.2.0/include"
        ],
        "defines": [],
        "cStandard": "gnu99",
        "cppStandard": "gnu++14",
        "intelliSenseMode": "linux-gcc-x86",
        "compilerPath": "/home/username/opt/cross/bin/i686-elf-gcc",
        "compilerArgs": [
            "-ffreestanding"
        ]
}

I noticed that intelliSenseMode affects this, because if I put something unrelated to Linux there, then everything is fine, but I do not know how to choose just x86-gcc there, without binding to my or another platform.

[sean-mcmanus]

This is related to #4653 , not sure if we need a separate issue for gcc on a non-Linux OS.

[sean-mcmanus]

Our extension will define it internally when a linux intelliSenseMode is used.